ZSM-5 molecular sieve catalyst as well as preparation method and application thereof
By ion-exchange and loading of metal oxide active components on ZSM-5 molecular sieve support, a chemically controllable nano-molecular sieve catalyst was constructed, which solved the problems of high reaction temperature, poor product selectivity and insufficient catalyst stability in the catalytic cracking of waste plastics, and achieved a catalytic effect of high activity and high selectivity at low temperature.
Patent Information
- Application Number
- CN202511139663.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-14
- Publication Date
- 2025-11-28
AI Technical Summary
Existing catalytic cracking technologies for waste plastics suffer from problems such as high reaction temperatures, poor product selectivity, insufficient catalyst stability, and limited capacity to process chlorine-containing plastics. In particular, their catalytic activity is insufficient under low-temperature conditions, making it difficult to meet the industrial demand for energy conservation and emission reduction.
A ZSM-5 molecular sieve catalyst with metal ion exchange and metal oxide loading was constructed by ion exchange and loading of metal oxide active components on a ZSM-5 molecular sieve support. The chemical environment of the catalyst was controlled, and its acidity and redox properties were regulated to achieve targeted catalytic cracking of different types of waste plastics.
The catalyst exhibits significantly improved activity and stability under low-temperature conditions, enhanced product selectivity and catalytic efficiency, effectively removed chlorides, and improved the resource utilization efficiency of waste plastics.
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Figure CN121016833A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of waste plastic treatment, in particular to a ZSM-5 molecular sieve catalyst, a preparation method and application thereof. BACKGROUND
[0002] With the continuous growth of global plastic consumption, waste plastic treatment has become an urgent environmental problem. After use, plastics are difficult to degrade naturally, and harmful ingredients can invade soil, water sources and the atmosphere, causing serious harm to the human living environment. Among the many waste plastic treatment methods, catalytic cracking technology has attracted much attention because it can convert waste plastics into high-value chemicals and fuels.
[0003] Traditional plastic cracking methods mainly use thermal cracking technology, which usually requires high temperature (about 450-800℃) and high energy consumption. In addition, the product distribution is wide, the selectivity is poor, and it is difficult to obtain high-value target products. At the same time, the coke produced in the thermal cracking process is easy to deposit on the surface of the reactor, reducing the heat transfer efficiency and affecting the long-term operation performance of the equipment.
[0004] Although the existing catalytic cracking technology has reduced the reaction temperature to some extent and improved the product selectivity, there are still many problems. First, most catalysts are easily deactivated under high-temperature reaction conditions, with poor catalytic stability, and frequent regeneration, increasing the operating cost. Second, the existing catalysts have limited ability to handle chlorine-containing plastics (such as PVC), and the release of hydrogen chloride during the catalytic process not only corrodes the equipment but also reduces the product quality, and causes secondary pollution to the environment. In addition, the morphology of the catalyst is irregular, resulting in uneven distribution of active sites and low utilization of active sites, which reduces the catalytic efficiency.
[0005] ZSM-5 molecular sieve has a good application prospect in the field of catalytic conversion of hydrocarbons due to its special pore structure and strong acidity. However, when single ZSM-5 molecular sieve is used for waste plastic catalytic cracking, it still faces problems such as insufficient activity, poor selectivity, and low stability. In particular, at low temperatures (<400℃), its catalytic activity is obviously insufficient, making it difficult to meet the industrial demand for energy saving and consumption reduction. At the same time, traditional ZSM-5 molecular sieve catalysts are easily deactivated by the poisoning effect of chlorides when treating chlorine-containing plastics.
[0006] In summary, the existing waste plastic catalytic cracking technology still faces technical problems such as high reaction temperature, poor product selectivity, insufficient catalyst stability, and limited ability to handle chlorine-containing plastics. Therefore, it is urgent to develop a new catalyst with low temperature high activity, good selectivity, excellent stability, and effective chlorine removal ability to improve the efficiency and economy of waste plastic catalytic cracking and promote the resource utilization of waste plastics. SUMMARY
[0007] The present application aims to provide a ZSM-5 molecular sieve catalyst with metal ions exchanged and reloaded metal oxides and a preparation method thereof, and aims to solve the technical problems of high reaction temperature and poor product selectivity in the existing waste plastic catalytic cracking process.
[0008] To solve the above technical problems, the present application provides a ZSM-5 molecular sieve catalyst, which comprises a ZSM-5 molecular sieve as a carrier, at least one kind of metal ion contained in the channel of the carrier, and at least one kind of metal oxide active component loaded on the surface of the carrier, the mass percentage of the metal oxide active component being less than 20wt.%.
[0009] Optionally, the ZSM-5 molecular sieve carrier has adjustable acidity, and the molar ratio of silicon to aluminum is 10-300.
[0010] Optionally, the metal ion is selected from V, Fe, Ni, Zr, Co, Ru, Rh, In, Ga, Pt, Pd or Ir.
[0011] Optionally, the metal oxide active component is selected from La, Ce, Nd, Al, Sm or Pr.
[0012] Optionally, the morphology structure of the ZSM-5 molecular sieve includes rectangular crystal and flat cylindrical crystal.
[0013] The present application also provides a method for preparing the above-mentioned ZSM-5 molecular sieve catalyst, which comprises the following steps:
[0014] Preparation of a ZSM-5 molecular sieve carrier;
[0015] Ion exchange treatment of the ZSM-5 molecular sieve carrier with a solution containing at least one kind of metal salt;
[0016] Chemical bath deposition treatment of the ZSM-5 molecular sieve carrier after ion exchange treatment with a solution containing at least one kind of metal salt;
[0017] Calcination to obtain the ZSM-5 molecular sieve catalyst.
[0018] Optionally, the step of preparing the ZSM-5 molecular sieve carrier comprises:
[0019] Mixing a template agent with a silicon source to form a first mixture;
[0020] Mixing an aluminum source with water to form a second mixture;
[0021] Mixing the first mixture with the second mixture to form a third mixture;
[0022] Hydrothermal treatment of the third mixture;
[0023] The product after hydrothermal treatment was dried and calcined to obtain the ZSM-5 molecular sieve support.
[0024] Optionally, the template agent is tetrapropylammonium hydroxide, the silicon source is tetraethyl orthosilicate, and the aluminum source is selected from sodium aluminate and / or aluminum isopropoxide.
[0025] Optionally, the hydrothermal treatment temperature is 160–200°C and the time is 40–80 hours; during the drying and calcination of the hydrothermally treated product, the calcination temperature is 500–600°C and the time is 6–12 hours.
[0026] Optionally, the calcination temperature in the process of obtaining the ZSM-5 molecular sieve catalyst after calcination is 400-550°C and the time is 2-6 hours.
[0027] The present invention also provides a method for catalytic cracking of waste plastics, which uses the above-mentioned ZSM-5 molecular sieve catalyst to catalytically crack the waste plastics at a temperature of 300 to 500°C.
[0028] Compared with the prior art, the present invention has at least the following technical effects:
[0029] This invention constructs a chemically controllable nanoscale molecular sieve catalyst by ion-exchange reloading of metal oxide active components onto a ZSM-5 molecular sieve support. This catalyst, by enhancing the intimacy and coupling of metal-acid sites and balancing the redox properties of the metal and the acidity of the molecular sieve, exhibits excellent low-temperature activity, high product selectivity, and good thermal stability. It can effectively promote the catalytic cracking of waste plastics at relatively low temperatures, significantly improving catalytic cracking efficiency and product quality.
[0030] Furthermore, by adjusting the silica-alumina ratio of the ZSM-5 molecular sieve and selecting different types of transition metals or noble metals for ion exchange followed by loading metal oxides onto the support surface, the acidity and redox properties of the catalyst can be precisely adjusted, achieving targeted catalytic cracking of different types of waste plastics. Simultaneously, because the catalyst is prepared first by ion exchange and then by chemical bath deposition, the transition metal or noble metal ions are uniformly dispersed in the molecular sieve channels and the active components of the metal oxides on the support surface, forming a synergistic mechanism: the large molecules of waste plastics first react with the active sites of the surface metal oxides, cracking into smaller molecules. These smaller molecules then enter the metal ion channels of the molecular sieve for further selective catalytic cracking into the target product, thus significantly improving the catalyst's activity and stability, providing a new technical solution for the efficient recycling of waste plastics. Attached Figure Description
[0031] Figure 1This is a flowchart of a method for preparing a ZSM-5 molecular sieve catalyst in an embodiment of the present invention. Detailed Implementation
[0032] The following description, with reference to schematic diagrams, illustrates a ZSM-5 molecular sieve catalyst, its preparation method, and its applications, wherein preferred embodiments of the invention are shown. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.
[0033] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.
[0034] Example 1
[0035] This invention provides a ZSM-5 molecular sieve catalytic cracking catalyst for waste plastics. The ZSM-5 molecular sieve catalyst is formed by first undergoing ion exchange on a ZSM-5 molecular sieve support and then loading a metal oxide.
[0036] The catalyst comprises a ZSM-5 molecular sieve as a support, wherein the pores of the support contain at least one metal ion, and at least one metal oxide active component is loaded on the surface of the support, wherein the mass percentage of the metal oxide active component is less than 20 wt.%.
[0037] In this embodiment of the invention, at least one metal ion is exchanged into the molecular sieve pores by ion exchange, and at least one metal oxide active component is loaded on the surface of the support. The molar mass of the metal ion exchanged into the molecular sieve pores is 0.01 to 0.5 mol / L, and the mass percentage of the metal oxide active component is less than 20 wt.%, preferably less than 15 wt.%.
[0038] The large molecules of waste plastics first react with the active sites of metal oxides on the surface, breaking them down into smaller molecules. These smaller molecules then enter the metal ion channels of the molecular sieve for further selective catalytic cracking into the target product, thereby significantly improving the activity and stability of the catalyst. The catalyst provided in this embodiment of the invention exhibits excellent resistance to deactivation, good stability, effective chloride removal capability, regular morphology, and high utilization rate of active sites.
[0039] In a specific example of the present invention, the support has adjustable acidity, with a silicon-to-aluminum molar ratio of 10–300. Preferably, the silicon-to-aluminum molar ratio is 100–200. The adjustable acidity enables the catalyst to exhibit higher selectivity and activity during the pyrolysis of waste plastics. By adjusting the silicon-to-aluminum ratio, the acid strength and acid density of the ZSM-5 molecular sieve can be precisely controlled, thereby optimizing catalytic performance.
[0040] In another specific example of the present invention, the metal ion is selected from V, Fe, Ni, Zr, Co, Ru, Rh, In, Ga, Pt, Pd, or Ir, and the active component of the metal oxide is selected from La, Ce, Nd, Al, Sm, or Pr. Highly active metals exhibit excellent catalytic performance in the catalytic cracking of waste plastics, effectively reducing the cracking reaction temperature and improving the selectivity of the target product.
[0041] In another specific example of the present invention, the morphology of the ZSM-5 molecular sieve includes cuboid crystals and flat cylindrical crystals. The morphology of the ZSM-5 molecular sieve contains only a small amount of flat cylindrical crystals. This specific morphology allows the catalyst to have a larger external surface area and more exposed active sites, which is beneficial to improving catalytic activity and product selectivity.
[0042] Example 2
[0043] This invention provides a method for preparing the ZSM-5 molecular sieve catalyst provided in Example 1, comprising the following steps:
[0044] S1: Preparation of ZSM-5 molecular sieve support.
[0045] In this step, ZSM-5 molecular sieve supports with specific silicon-to-aluminum ratios and morphological structures are first prepared.
[0046] Specifically, it includes:
[0047] S1.1: The template agent is mixed with the silicon source to form a first mixture.
[0048] In a preferred embodiment, the template agent is tetrapropylammonium hydroxide and the silicon source is tetraethyl orthosilicate.
[0049] Specifically, 15.1-15.75 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours to form a homogeneous first mixture (solution A).
[0050] S1.2: Mix the aluminum source with water to form a second mixture.
[0051] In a preferred embodiment, the aluminum source is selected from sodium aluminate and / or aluminum isopropoxide. Specifically, according to the target silicon-aluminum ratio, an appropriate amount of aluminum source (such as 0.27–1.07 g of sodium aluminate or aluminum isopropoxide) is dissolved in 35.1 mL of deionized water and stirred at 90°C for 4 hours to form a homogeneous second mixture (solution B).
[0052] S1.3: Mix the first mixture with the second mixture to form a third mixture.
[0053] Solution B was added dropwise to solution A, and then stirred at 45°C for 4 hours to obtain a third mixture (solution C). This slow mixing method helps to form a homogeneous gel precursor, laying the foundation for the subsequent crystallization process.
[0054] S1.4: Perform hydrothermal treatment on the third mixture.
[0055] The third mixture was transferred to a 100 mL polytetrafluoroethylene-lined reactor, and water was added to bring the volume up to the original solution volume. Hydrothermal treatment was then carried out under closed conditions.
[0056] In a preferred embodiment, the hydrothermal treatment is performed at a temperature of 160–200°C for 40–80 hours.
[0057] Specifically, it can be hydrothermally treated at 180°C for 60 hours.
[0058] S1.5: The product after hydrothermal treatment is dried and calcined to obtain the ZSM-5 molecular sieve support.
[0059] After hydrothermal treatment, the product is centrifuged and washed, dried overnight in an 80°C forced-air drying oven, and then calcined after thorough grinding.
[0060] In a preferred embodiment, the calcination temperature is 500–600°C and the time is 6–12 hours.
[0061] Specifically, ZSM-5 molecular sieve supports with specific structures and properties can be obtained by calcining at 550℃ for 7 to 10 hours at a heating rate of 5℃ / min.
[0062] S2: The ZSM-5 molecular sieve support is subjected to ion exchange treatment with a solution containing at least one metal salt.
[0063] In step S2, metal ions are introduced into the ZSM-5 molecular sieve pore framework using an ion exchange method.
[0064] In a preferred example, the metal salt used in the ion exchange process is selected from transition metals or noble metals, including V, Fe, Ni, Zr, Co, Ru, Rh, In, Ga, Pt, Pd, or Ir.
[0065] The ion exchange process employs the ion exchange method.
[0066] Specifically, the ZSM-5 molecular sieve support prepared in step S1 is mixed with a 0.01–0.5 mol / L metal salt solution (such as ferric nitrate hexahydrate, ruthenium chloride, ammonium metavanadate, nickel nitrate hexahydrate, etc.) in a suitable solvent (such as water), and subjected to ion exchange reflux treatment at 70–80 °C for 12 hours.
[0067] During ion exchange, metal ions can fully interact with the active sites in ZSM-5 molecular sieves to form a stable metal-molecular sieve composite structure.
[0068] In a specific example, two different metal salts can be used simultaneously for exchange, such as a combination of ferric nitrate hexahydrate and ammonium metavanadate, or a combination of ferric nitrate hexahydrate and nickel nitrate hexahydrate. This bimetallic exchange method can further improve the performance of the catalyst through a synergistic effect.
[0069] S3: The ZSM-5 molecular sieve support after ion exchange treatment is subjected to chemical bath deposition with a solution containing at least one metal salt.
[0070] In step S3, the active component of metal oxide is introduced into the surface of the ion-exchanged ZSM-5 molecular sieve support by chemical bath deposition.
[0071] In a preferred embodiment, the metal salt used in the chemical bath deposition process is selected from La, Ce, Nd, Al, Sm, or Pr.
[0072] The load treatment process employs a chemical bath deposition method.
[0073] Specifically, the ion-exchanged ZSM-5 molecular sieve support prepared in step S2 is mixed with a metal salt solution (such as lanthanum chloride, cerium nitrate hexahydrate, neodymium nitrate hexahydrate, aluminum nitrate nonahydrate, etc.) in a suitable solvent (such as ethanol) and subjected to impregnation and reflux treatment at 60°C for 7 hours.
[0074] During the chemical bath deposition process, the metal oxide can fully interact with the active sites in the ZSM-5 molecular sieve after ion exchange to form a stable metal-molecular sieve composite structure.
[0075] In a specific example, two different metal salts can be used simultaneously for impregnation loading, such as a combination of cerium nitrate hexahydrate and lanthanum chloride, or a combination of cerium nitrate hexahydrate and neodymium nitrate hexahydrate. This bimetallic oxide loading method can further improve the selectivity of the catalyst through a synergistic effect.
[0076] S4: The product obtained from calcination step S3 is used to obtain the catalyst.
[0077] After chemical bath deposition, the solvent was removed by rotary evaporation at 45°C. The product was then dried overnight in an 80°C forced-air drying oven, thoroughly ground, and then calcined.
[0078] In a preferred embodiment, the calcination temperature is 400–550°C, and the time is 2–6 hours. Specifically, the calcination can be carried out at 500°C for 4 hours at a heating rate of 5°C / min to obtain the ion-exchange metal-supported ZSM-5 molecular sieve catalyst.
[0079] The preparation method provided in this embodiment can yield a ZSM-5 molecular sieve catalyst with highly dispersed metal active sites. The ion-exchange active sites and metal oxides in the catalyst can form a synergistic effect with the acidic sites of the molecular sieve, significantly improving the efficiency and selectivity of catalytic cracking of waste plastics.
[0080] The present invention also provides a method for catalytic cracking of waste plastics, namely, using the above-mentioned catalyst to catalytically crack the waste plastics at a temperature of 300-500°C.
[0081] Specifically, the prepared catalyst can be granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for pyrolysis. Under a nitrogen atmosphere, the catalyst is heated at a heating rate of 10℃ / min and held at the final temperature for 20 min to investigate its effect on the distribution of plastic pyrolysis products.
[0082] Example 3
[0083] This invention systematically investigated the effects of different parameters on the performance of ZSM-5 molecular sieve catalysts after ion exchange and subsequent loading with metal oxides through 12 experimental examples. These examples were designed based on four key variables: the type and amount of aluminum source in the support preparation, the type and combination of ion exchange metals, the type and combination of loaded metal oxides, and the silica-alumina ratio of the molecular sieve.
[0084] Experimental Example 1
[0085] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.27 g of sodium aluminate was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0086] 1g of the product obtained above was impregnated and refluxed with 100mL of 0.025mol / L ferric nitrate hexahydrate solution at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the iron ion exchange ZSM-5 molecular sieve catalyst.
[0087] 1g of the product obtained above and 0.0152g of lanthanum chloride were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst with iron ion exchange and re-supported lanthanum oxide.
[0088] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0089] Experimental Example 2
[0090] 15.10 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.53 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0091] 1g of the product obtained above was impregnated and refluxed with 100mL of 0.025mol / L ferric nitrate hexahydrate solution at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the iron ion exchange ZSM-5 molecular sieve catalyst.
[0092] 1g of the product obtained above and 0.0152g of lanthanum chloride were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain an ion-exchange ZSM-5 molecular sieve catalyst with iron ion exchange and re-supported lanthanum oxide.
[0093] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0094] Experimental Example 3
[0095] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 1.07 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, then milled, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0096] 1g of the product obtained above was impregnated and refluxed with 100mL of 0.025mol / L ferric nitrate hexahydrate solution at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the iron ion exchange ZSM-5 molecular sieve catalyst.
[0097] 1 g of the product obtained above and 0.0152 g of lanthanum chloride were added to 25 mL of ethanol solution and impregnated and refluxed at 60 °C for 7 hours. Then, the mixture was rotary evaporated at 45 °C and dried overnight in an 80 °C forced-air drying oven. After grinding, the mixture was calcined at 500 °C (heating rate of 5 °C / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst with iron ion exchange and re-supported lanthanum oxide.
[0098] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0099] Experiment Example 4
[0100] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.27 g of sodium aluminate was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0101] 1g of the product obtained above and 100mL of 0.025mol / L ruthenium chloride solution were impregnated and refluxed at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ruthenium ion-exchanged ZSM-5 molecular sieve catalyst.
[0102] 1g of the product obtained above and 0.125g of cerium nitrate hexahydrate were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst with ruthenium ion exchange and reloaded cerium oxide.
[0103] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0104] Experimental Example 5
[0105] 15.10 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.53 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0106] 1g of the product obtained above and 100mL of 0.025mol / L ruthenium chloride solution were impregnated and refluxed at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ruthenium ion-exchanged ZSM-5 molecular sieve catalyst.
[0107] 1g of the product obtained above and 0.125g of cerium nitrate hexahydrate were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst with ruthenium ion exchange and reloaded cerium oxide.
[0108] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0109] Experimental Example 6
[0110] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 1.07 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, then milled, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0111] 1g of the product obtained above and 100mL of 0.025mol / L ruthenium chloride solution were impregnated and refluxed at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ruthenium ion-exchanged ZSM-5 molecular sieve catalyst.
[0112] 1g of the product obtained above and 0.125g of cerium nitrate hexahydrate were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst with ruthenium ion exchange and reloaded cerium oxide.
[0113] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0114] Experimental Example 7
[0115] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.27 g of sodium aluminate was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0116] 1g of the product obtained above was impregnated and refluxed with 50ml of 0.025mol ammonium metavanadate and 50ml of 0.025mol ferric nitrate hexahydrate at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ forced-air drying oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst after vanadium-iron bimetallic ion exchange.
[0117] 1 g of the product obtained above, 0.0152 g of lanthanum chloride, and 0.125 g of cerium nitrate hexahydrate were added to 25 mL of ethanol solution and impregnated under reflux at 60 °C for 7 hours. The mixture was then rotary evaporated at 45 °C, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 500 °C (heating rate of 5 °C / min) for 4 hours to obtain a ZSM-5 molecular sieve catalyst supported on vanadium-iron bimetallic ion exchange and lanthanum-cerium bimetallic oxide.
[0118] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0119] Experimental Example 8
[0120] 15.10 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.53 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0121] 1g of the product obtained above was impregnated and refluxed with 50ml of 0.025mol ammonium metavanadate and 50ml of 0.025mol ferric nitrate hexahydrate at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ forced-air drying oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst after vanadium-iron bimetallic ion exchange.
[0122] 1 g of the product obtained above, 0.0152 g of lanthanum chloride, and 0.125 g of cerium nitrate hexahydrate were added to 25 mL of ethanol solution and impregnated under reflux at 60 °C for 7 hours. The mixture was then rotary evaporated at 45 °C, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 500 °C (heating rate of 5 °C / min) for 4 hours to obtain a ZSM-5 molecular sieve catalyst supported on vanadium-iron bimetallic ion exchange and lanthanum-cerium bimetallic oxide.
[0123] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0124] Experimental Example 9
[0125] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 1.07 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, then milled, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0126] 1g of the product obtained above was impregnated and refluxed with 50ml of 0.025mol ammonium metavanadate and 50ml of 0.025mol ferric nitrate hexahydrate at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ forced-air drying oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the ZSM-5 molecular sieve catalyst after vanadium-iron bimetallic ion exchange.
[0127] 1 g of the product obtained above, 0.0152 g of lanthanum chloride, and 0.125 g of cerium nitrate hexahydrate were added to 25 mL of ethanol solution and impregnated under reflux at 60 °C for 7 hours. The mixture was then rotary evaporated at 45 °C, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 500 °C (heating rate of 5 °C / min) for 4 hours to obtain a ZSM-5 molecular sieve catalyst supported on vanadium-iron bimetallic ion exchange and lanthanum-cerium bimetallic oxide.
[0128] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0129] Experimental Example 10
[0130] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours (solution A); similarly, 0.27 g of sodium aluminate was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours (solution B); solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours (solution C), with deionized water used to replenish the evaporated volume; the resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours, centrifuged and washed three times with water, dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0131] 1g of the product obtained above was impregnated and refluxed with 50mL of 0.025mol / L nickel nitrate hexahydrate and 50mL of 0.025mol / L ferric nitrate hexahydrate at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ forced-air drying oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the nickel-iron bimetallic ion-exchange ZSM-5 molecular sieve catalyst.
[0132] 1g of the product obtained above, 0.125g of cerium nitrate hexahydrate, and 0.145g of samarium nitrate hexahydrate were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain a ZSM-5 molecular sieve catalyst supported on nickel-iron bimetallic ion exchange samarium-cerium bimetallic oxide.
[0133] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0134] Experimental Example 11
[0135] 15.10 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours to obtain solution A. Similarly, 0.53 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours to obtain solution B. Solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours. The volume evaporated was replenished with deionized water. The resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours. After centrifugation and washing three times with water, the solution was dried overnight in an 80 °C forced-air drying oven, thoroughly ground, and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0136] 1g of the product obtained above was impregnated and refluxed with 50ml of 0.025mol / L nickel nitrate hexahydrate and 50ml of 0.025mol / L ferric nitrate hexahydrate at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ forced-air drying oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the nickel-iron bimetallic ion-exchange ZSM-5 molecular sieve catalyst.
[0137] 1g of the product obtained above, 0.125g of cerium nitrate hexahydrate, and 0.145g of samarium nitrate hexahydrate were added to 25mL of ethanol solution and impregnated and refluxed at 60℃ for 7 hours. The mixture was then rotary evaporated at 45℃, dried overnight in an 80℃ forced-air drying oven, thoroughly ground, and calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain a ZSM-5 molecular sieve catalyst supported on nickel-iron bimetallic ion exchange samarium-cerium bimetallic oxide.
[0138] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0139] Experimental Example 12
[0140] 15.1 mL of tetrapropylammonium hydroxide and 15.75 mL of tetraethyl orthosilicate were stirred at 45 °C for 4 hours to obtain solution A. Similarly, 1.07 g of aluminum isopropoxide was dissolved in 35.1 mL of deionized water and stirred at 90 °C for 4 hours to obtain solution B. Solution B was added dropwise to solution A, and then stirred at 45 °C for 4 hours. The volume evaporated was replenished with deionized water. The resulting solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally heated at 180 °C for 60 hours. After centrifugation and washing three times with water, the solution was dried overnight in an 80 °C forced-air drying oven. Then, it was milled and calcined at 550 °C (heating rate of 5 °C / min) for 7 hours to obtain the product for later use.
[0141] 1g of the product obtained above was impregnated and refluxed with 50mL of 0.025mol / L nickel nitrate hexahydrate and 50mL of 0.025mol / L ferric nitrate hexahydrate at 70℃ for 7 hours. After centrifugation and washing until neutral, the product was dried overnight in an 80℃ forced-air drying oven. After thorough grinding, the product was calcined at 500℃ (heating rate of 5℃ / min) for 4 hours to obtain the nickel-iron bimetallic ion-exchange ZSM-5 molecular sieve catalyst.
[0142] 1 g of the product obtained above, 0.125 g of cerium nitrate hexahydrate, and 0.145 g of samarium nitrate hexahydrate were added to 25 mL of ethanol solution and impregnated under reflux at 60 °C for 7 hours. Then, the mixture was rotary evaporated at 45 °C and dried overnight in an oven at 80 °C. After grinding, the mixture was calcined at 500 °C (heating rate of 5 °C / min) for 4 hours to obtain a ZSM-5 molecular sieve catalyst supported on nickel-iron bimetallic ion exchange samarium-cerium bimetallic oxide.
[0143] Catalytic cracking activity test of the catalyst: The catalyst prepared above was granulated to 40-60 mesh and placed in a temperature-controlled fixed-bed reactor for activity and product selectivity testing. The reaction temperature range was 20-800℃ and the space velocity was 100,000 h⁻¹. -1 The effect of catalyst addition on the distribution of plastic pyrolysis products was investigated under a nitrogen atmosphere with a heating rate of 10 °C / min and a holding time at the final temperature for 20 min.
[0144] In all of the above experimental examples 1-12, tetrapropylammonium hydroxide was used as a template agent and tetraethyl orthosilicate as a silicon source, but the type and amount of aluminum source differed:
[0145] Sodium aluminate (0.27 g) was used in Experiments 1, 4, 7 and 10 to represent low aluminum content systems;
[0146] Aluminum isopropoxide (0.53 g) was used in Experiments 2, 5, 8 and 11, representing systems with medium aluminum content;
[0147] Aluminum isopropoxide (1.07 g) was used in Experiments 3, 6, 9 and 12, representing high aluminum content systems.
[0148] As the aluminum content increases, the acidity of the molecular sieve increases, but this may affect the regularity of its crystal structure and thermal stability.
[0149] The above experimental examples 1-12 also investigated the effects of single-metal and bimetallic ion exchange and the loading of single-metal oxides and bimetallic oxides:
[0150] Single-metal iron ion exchange and reloading of single-metal lanthanum oxide (Experimental Examples 1-3): The use of ferric nitrate hexahydrate and lanthanum chloride has good catalytic activity and economy;
[0151] Ruthenium ion exchange with single metal and then loaded with single metal cerium oxide (Experimental Examples 4-6): Ruthenium chloride was used as a noble metal catalyst with extremely high catalytic activity; cerium nitrate hexahydrate was used with extremely high dispersibility and sample storage capacity.
[0152] Bimetallic vanadium-iron ion exchange with reloading of bimetallic lanthanum-cerium oxide (Experimental Examples 7-9): Using a combination of ammonium metavanadate and ferric nitrate hexahydrate ion exchange, bimetallic lanthanum-cerium oxide is reloaded to enhance catalytic performance through synergistic effect.
[0153] Bimetallic nickel-iron ion exchange loaded bimetallic cerium-samarium oxide (Experimental Examples 10-12): A combination of nickel nitrate hexahydrate and ferric nitrate hexahydrate ion exchange was used, and then loaded with bimetallic lanthanum-cerium oxide, balancing activity and cost.
[0154] We systematically compared the effects of different metals and metal oxides and their combinations on the catalytic cracking performance of waste plastics, especially the synergistic effect between metals on the regulation of product selectivity.
[0155] The above experimental examples 1-12 also achieved systematic control of the silicon-to-aluminum ratio of ZSM-5 molecular sieve by adjusting the amount of aluminum source used:
[0156] High silicon-to-aluminum ratio (Experimental Examples 1, 4, 7, 10): Low aluminum content, relatively weak acidity, and good thermal stability;
[0157] Medium silicon-to-aluminum ratio (Experimental Examples 2, 5, 8, 11): Moderate aluminum content, balanced acidity and stability;
[0158] Low silicon-to-aluminum ratio (Experimental Examples 3, 6, 9, 12): High aluminum content, strong acidity, but thermal stability may decrease.
[0159] The silicon-to-aluminum ratio is a key factor affecting the catalytic performance of molecular sieves. It directly determines the acidity strength and distribution of molecular sieves, thereby affecting the reaction pathway and product selectivity in the catalytic cracking process.
[0160] In summary, the ZSM-5 molecular sieve catalyst provided by this invention, prepared by metal ion exchange followed by loading metal oxides onto the support surface, exhibits low-temperature catalytic activity, high product selectivity, and excellent thermal stability. Through a metal-acid synergistic effect, the catalyst significantly reduces the temperature required for waste plastic pyrolysis, achieving efficient pyrolysis at temperatures lower than traditional pyrolysis temperatures (300–450°C), thus saving energy consumption. The catalyst can directionally catalyze the pyrolysis of waste plastics to generate light hydrocarbons, reducing the formation of coke and heavy hydrocarbons and improving the yield of the target product. The high dispersion and stability of the active components, metal ions and metal oxides, on the ZSM-5 molecular sieve framework and support surface ensure that the ZSM-5 molecular sieve catalyst maintains its activity under high-temperature reaction conditions, exhibiting a long service life. The ZSM-5 molecular sieve catalyst demonstrates good catalytic pyrolysis effects on various common waste plastics such as polyethylene, polypropylene, and polystyrene, with a wide range of applications. The catalyst preparation method provided by this invention is simple and convenient to operate, facilitating industrial production and application.
[0161] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A ZSM-5 molecular sieve catalyst, characterized in that: The catalyst comprises a ZSM-5 molecular sieve as a support, wherein the pores of the support contain at least one metal ion, and at least one metal oxide active component is loaded on the surface of the support, wherein the mass percentage of the metal oxide active component is less than 20 wt.%.
2. The ZSM-5 molecular sieve catalyst according to claim 1, characterized in that: The carrier has adjustable acidity, and its silicon-aluminum molar ratio is 10–300.
3. The ZSM-5 molecular sieve catalyst according to claim 1, characterized in that: The metal ions are selected from V, Fe, Ni, Zr, Co, Ru, Rh, In, Ga, Pt, Pd, or Ir.
4. The ZSM-5 molecular sieve catalyst according to claim 1, characterized in that: The active metal oxide component is selected from La, Ce, Nd, Al, Sm, or Pr.
5. The ZSM-5 molecular sieve catalyst according to claim 1, characterized in that: The ZSM-5 molecular sieve has a morphological structure including cuboid crystals and flat cylindrical crystals.
6. A method for preparing the ZSM-5 molecular sieve catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: Preparation of ZSM-5 molecular sieve support; The ZSM-5 molecular sieve support was subjected to ion exchange treatment with a solution containing at least one metal salt; The ZSM-5 molecular sieve support, after undergoing ion exchange treatment, is subjected to chemical bath deposition with a solution containing at least one metal salt. The ZSM-5 molecular sieve catalyst was obtained after calcination.
7. The method according to claim 6, characterized in that: The steps for preparing the ZSM-5 molecular sieve support include: The template agent is mixed with the silicon source to form a first mixture; The aluminum source is mixed with water to form a second mixture; The first mixture is mixed with the second mixture to form a third mixture; The third mixture is subjected to hydrothermal treatment; The product after hydrothermal treatment was dried and calcined to obtain the ZSM-5 molecular sieve support.
8. The method according to claim 7, characterized in that: The template agent is tetrapropylammonium hydroxide, the silicon source is tetraethyl orthosilicate, and the aluminum source is selected from sodium aluminate and / or aluminum isopropoxide.
9. The method according to claim 7, characterized in that: The hydrothermal treatment is performed at a temperature of 160–200°C for 40–80 hours; during the drying and calcination of the hydrothermally treated product, the calcination temperature is 500–600°C for 6–12 hours.
10. The method according to claim 6, characterized in that: The calcination temperature for obtaining the ZSM-5 molecular sieve catalyst after calcination is 400-550℃, and the time is 2-6 hours.
11. A method for catalytic pyrolysis of waste plastics, characterized in that: Waste plastics are catalytically cracked using the ZSM-5 molecular sieve catalyst according to any one of claims 1-5 at a temperature of 300-500°C.